Articles | Volume 10, issue 22
Atmos. Chem. Phys., 10, 11261–11276, 2010
Atmos. Chem. Phys., 10, 11261–11276, 2010

Research article 30 Nov 2010

Research article | 30 Nov 2010

Global modeling of organic aerosol: the importance of reactive nitrogen (NOx and NO3)

H. O. T. Pye1,*, A. W. H. Chan1,**, M. P. Barkley2,***, and J. H. Seinfeld1 H. O. T. Pye et al.
  • 1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
  • 2School of GeoSciences, University of Edinburgh, Edinburgh, Scotland, UK
  • *now at: Atmospheric Modeling and Analysis Division, National Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
  • **now at: Department of Environmental Science, Policy and Management, University of California, Berkeley, California, USA
  • ***now at: EOS Group, Department of Physics and Astronomy, University of Leicester, UK

Abstract. Reactive nitrogen compounds, specifically NOx and NO3, likely influence global organic aerosol levels. To assess these interactions, GEOS-Chem, a chemical transport model, is updated to include improved biogenic emissions (following MEGAN v2.1/2.04), a new organic aerosol tracer lumping scheme, aerosol from nitrate radical (NO3) oxidation of isoprene, and NOx-dependent monoterpene and sesquiterpene aerosol yields. As a result of significant nighttime terpene emissions, fast reaction of monoterpenes with the nitrate radical, and relatively high aerosol yields from NO3 oxidation, biogenic hydrocarbon-NO3 reactions are expected to be a major contributor to surface level aerosol concentrations in anthropogenically influenced areas such as the United States. By including aerosol from nitrate radical oxidation in GEOS-Chem, terpene (monoterpene + sesquiterpene) aerosol approximately doubles and isoprene aerosol is enhanced by 30 to 40% in the Southeast United States. In terms of the global budget of organic aerosol, however, aerosol from nitrate radical oxidation is somewhat minor (slightly more than 3 Tg/yr) due to the relatively high volatility of organic-NO3 oxidation products in the yield parameterization. Globally, 69 to 88 Tg/yr of organic aerosol is predicted to be produced annually, of which 14–15 Tg/yr is from oxidation of monoterpenes and sesquiterpenes and 8–9 Tg/yr from isoprene.

Final-revised paper